An electrochemical cell has two electrodes, the anode and the cathode, separated by an electrolyte. In a traditional electrochemical cell, materials in these electrodes are both electronically and chemically active. The anode is a chemical reductant and the cathode is a chemical oxidant. Both the anode and the cathode are able to gain and lose ions, typically the same ion, which is referred to as the working cation of the battery. The electrolyte is a conductor of the working cation, but normally it is not able to gain and lose ions. The electrolyte is an electronic insulator, it does not allow the movement of electrons within the battery. In a traditional electrochemical cell, both or at least one of the anode and the cathode contain the working cation prior to cycling of the electrochemical cell.
The electrochemical cell operates via a reaction between the two electrodes that has an electronic and an ionic component. The electrolyte conducts the working cation inside the cell and forces electrons also involved in the reaction to pass through an external circuit.
A battery may be a simple electrochemical cell, or it may be a combination of multiple electrochemical cells.
Rechargeable electrochemical cells and rechargeable batteries containing such electrochemical cells are typically charged using electrical energy from an external power source.